A new vaccine aimed at combating the Ebola virus strain that has claimed hundreds of lives in the Democratic Republic of Congo this year has commenced human clinical trials in the United Kingdom.
Developed by researchers at the University of Oxford, this experimental vaccine is now in the human testing phase. Researchers are optimistic that it could be effective against the Bundibugyo Ebolavirus strain currently causing an outbreak in the African nation.
The vaccine, named ChAdOx BDBV,
is being evaluated in a trial led by scientists from the Oxford Vaccine Group and the Pandemic Sciences Institute. The trial aims to determine the vaccine’s safety and the strength of the immune response it triggers. It will involve 50 healthy adult volunteers and marks the first clinical assessment of a vaccine developed specifically for the Bundibugyo ebolavirus.
The swift advancement of this vaccine to human trials is a reflection of the lessons learned during the COVID-19 pandemic, where flexible vaccine technologies allowed for rapid responses to new infectious threats. ChAdOx BDBV utilizes Oxford’s chimpanzee adenovirus vector platform, the same technology behind the Oxford-AstraZeneca COVID-19 vaccine.
The urgency of this program arises from a significant gap in Ebola preparedness. While an Ebola vaccine exists, it does not offer protection against all Ebola virus strains.
Currently, the only licensed Ebola vaccine, Ervebo (rVSV-ZEBOV), is designed to protect against Zaire ebolavirus, the strain that caused the 2014–2016 Ebola outbreak in West Africa, resulting in over 11,000 deaths. This vaccine has been very effective in preventing disease from the Zaire ebolavirus and is a key tool in outbreaks through ring vaccination strategies, where exposed individuals and their contacts are vaccinated.
However, Ebola is caused by several distinct virus species within the Ebola virus family, including Zaire ebolavirus, Sudan ebolavirus, and Bundibugyo ebolavirus. These viruses vary genetically, meaning immunity against one species does not necessarily protect against another.
Consequently, Ervebo is not approved for Bundibugyo ebolavirus and is unlikely to provide adequate protection against the strain currently affecting the DRC.
This situation has left public health teams without access to an approved vaccine specifically tailored to the virus causing infections. Instead, outbreak control has relied on rapid diagnosis, contact tracing, infection prevention measures, supportive care, and new medical countermeasures development.
The Oxford vaccine program is part of a broader initiative to address this vulnerability. Researchers hope that if the Phase I trial proves the vaccine is safe and generates a strong immune response, further studies could assess its protective efficacy in future outbreaks.
Early-stage vaccine trials primarily aim to establish safety and gauge immune responses rather than demonstrate effectiveness. Nonetheless, this first human trial is a significant step toward enhancing Ebola vaccine preparedness beyond a single viral strain.
The ongoing Bundibugyo ebolavirus outbreak underscores a persistent challenge in infectious disease preparedness: vaccines against one pathogen variant may not protect against closely related viruses that arise later. Expanding the vaccine portfolio could ensure quicker and more targeted responses to future Ebola outbreaks.
While an effective vaccine exists for the Zaire Ebolavirus strain, it is ineffective against Bundibugyo and other Ebola strains.
The current outbreak has resulted in over 800 deaths and more than 2,000 infections, according to the latest World Health Organization statistics from mid-July.
